Ultrasonic measuring method and ultrasonic measuring apparatus

Abstract

An ultrasonic measuring method includes: (A) receiving a coded spread spectrum ultrasonic signal in at least two receivers, and generating at least two received signals; (B) performing an quadrature detection on the received signals using the carrier frequency, and producing I and Q components of the received signals; (C) performing phase difference processing on the I and Q components with a coding period synchronized with that of the carrier frequency, and obtaining I′ and Q′ components from which a phase shift caused by a Doppler shift has been canceled; (D) despreading the I′ and Q′ components signals using different codes at time intervals synchronized with the carrier frequency, and obtaining despread I″ and Q″ components; (E) computing the amplitude and phase information based on the I″ and Q″ components; and (F) calculating the propagation distance and/or orientation of the ultrasonic wave based on the amplitude and phase information.

Description

[0001]This is a continuation of International Application No. PCT / JP2011 / 000871, with an international filing date of Feb. 17, 2011, which claims priority of Japanese Patent Application No. 2010-033112, filed on Feb. 18, 2010, the contents of which are hereby incorporated by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to a method and apparatus for ultrasonic measuring. More particularly, the present invention relates to a measuring method and apparatus that can accurately estimate the propagation distance or propagation direction of an ultrasonic wave by using a spread spectrum coded ultrasonic wave even when there is a relative velocity between the object of measurement and the measuring apparatus.[0004]2. Description of the Related Art[0005]An ultrasonic measuring apparatus includes a transmitter to send out an ultrasonic wave and a receiver to receive the ultrasonic wave and estimates the distance between the transmitter...

AI Technical Summary

Benefits of technology

[0020]It is therefore an object of the present invention to provide an ultrasonic measuring apparatus and method that can get measurements done accurately through sim

Problems solved by technology

In an environment where there are a number of such ultrasonic measuring apparatuses, the ultrasonic waves transmitted simultaneously by the respective ultrasonic measuring apparatuses would interfere with each other, thus possibly causing measurement errors.

If a Doppler shift is produced, however, the peak of correlation will decrease significantly and the correlation noise in the ranges before and after the peak will also have raised levels.

As a result, the SNR will drop steeply.

According to that method, however, it is still difficult to compensate for the Doppler shift perfectly and recover the correlation gain.

As a result, the size and cost of the hardware to use will rise too much to apply that technique to a consumer electronic device easily.

That is why to g

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